Faculty of Physics, University of Belgrade

Dragan Manić

Belgrade SHINE group

Ks0 analysis

in SHOE framework

Wroclaw analysis/calibration/software workshop

March the 8th, 2012

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 2 out of 11Dragan Manić, Belgrade SHINE team

pC 31GeV collisions runs:

09J Production8599 8600 8601 8602 8607 8608 8609 8610 86118612 8613 8614 8615 8616 8617 8650 8652 86538654 8659 8660 8661 8662 8663 8664 8665 86678668 8669 8670 8671 8672 8673 8674 8675 86768677 8678 8679 8711 8712 8713 8714 8715 87248725 8726 8727 8728 8729 8730 8731 8732 87338734 8735 8736 8737 8738 8739 8740 8741 87428743 8744 8745 8746 8747 8748 8749 8750 87518752 8753 8754 8755 8756 8757 8758 8760 87618762 8763 8764 8765 8766 8767 8768

Total number of events: 4240322

Data Set

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 3 out of 11Dragan Manić, Belgrade SHINE team

Description of the cuts

• Event cutsCut 0: T2 trigger cutCut 1: BPD Cut Cut 2: Main Vertex present Cut 3: Fitted vertex presentCut 4: Fitted vertex position correspond to target position; z=(-585, -575)cm

• Vertex cuts Cut 0: Vertex type: VZeroFFCut 1: Two daughter particlesCut 2: Different charge for daughter particlesCut 3: Distance between two daughter tracks at target z-plane more then 1.5 cmCut 4: Z distance between primary and secondary vertices is between 6 and 270 cmCut 5: V0 track based on secondary vertex to primary vertex distance is less then 0.6 cmCut 6: dE/dx cut

Cut 7: Set mass window between 0.4 and 0.6GeV

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 4 out of 11Dragan Manić, Belgrade SHINE team

Description of the cuts

Total number of events: 4240322----Event Cuts: ---

Event Cut 0: 746816 (17.61%)Event Cut 1: 1284357

(30.29%)Event Cut 2: 57432 (1.35%)

Event Cut 3: 788584 (18.60%)

Event Cut 4: 217739 (5.13%)

Number of Events left: 1145394 (27.01%)

Total number of vertices after event cuts: 11032161----Vertex Cuts: ---

Vertex Cut 0: 5832600 (52.87%)

Vertex Cut 1: 0 (0.00%)Vertex Cut 2: 1720706 (15.60%)Vertex Cut 3: 2230769 (20.22%)

Vertex Cut 4: 542494 (4.92%)

Vertex Cut 5: 594775 (5.39%)

Vertex Cut 6: 68202 (0.62%)Vertex Cut 7: 18116 (0.16%)

Number of Vertices left: 24499 (0.22%)

Total Cut 0 Cut 1 Cut 2 Cut 3 Cut 40

1000000

2000000

3000000

4000000

5000000

Total Cut 0 Cut 1 Cut 2 Cut 3 Cut 4 Cut 5 Cut 6 Cut 70

2000000

4000000

6000000

8000000

10000000

12000000

Number of events after cuts Number of vertices after cuts

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 5 out of 11Dragan Manić, Belgrade SHINE team

Distance between tracks

How it was. How it is now..

Distance cut at 1.5 cm

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 6 out of 11Dragan Manić, Belgrade SHINE team

Energy loss histograms

Before cut:

dE/dx histogram for positive particles

dE/dx histogram for negative particles

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 7 out of 11Dragan Manić, Belgrade SHINE team

Energy loss histograms

After cut:

dE/dx histogram for positive particles

dE/dx histogram for negative particles

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 8 out of 11Dragan Manić, Belgrade SHINE team

Fitting and quality of the analysis

Signal:

2)(

1

2)( 2

20mE

AEf

Background:

2110)( EaEaaEf

Global fit:

Signal + Background

Signal significance:BS

SSigSign

This estimation is based on data within ±2s from the signal pick(green vertical lines on the histograms).

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 9 out of 11Dragan Manić, Belgrade SHINE team

Comparison of the analyses

Zagreb ROOT61Sig significance = 33.5

Number of events: 935,030

Wroclaw SHOESig significance= 34.4

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 10 out of 11Dragan Manić, Belgrade SHINE team

Ks0 mass distribution

S = 8490B = 5105SigSignf = 72.9

Number of events: 4,240,322

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 11 out of 11Dragan Manić, Belgrade SHINE team

Thank You

Faculty of Physics, University of Belgrade

Wroclaw Analysis meeting, 08/03/2012Page 12 out of 11Dragan Manić, Belgrade SHINE team

Number of events: 500,000

Latest version of SHINE - v0r2p2

Cut 3: Distance between two daughter tracks at secondary vertex z-plane less then 1 cm